ON THE FRAGMENTATION PROCESSES IN THE METEOROID STREAMS

Radar observations of the main meteor showers in 1993-1995 carried out by a forward-scatter radiosystem Bologna-Lecce in Italy are analysed and discussed in terms of fragmentation effects even in the orbit of t he streams of interplanetary matter. The existence of very small parti cles in all meteoroid streams is revealed by counts of echoes of durat ion T less than or equal to 0.05 s. A progressive fragmentation is obs erved to precede in any meteoric complex, likely as a possible consequ ence of the disintegration of larger bodies in the stream. This disint egration appears to be more significant in some meteoric complexes (Ge minids, Leonids and delta-Aquarids), in connection With their differen tiated structure and composition.